Abstract
The mental continuity thesis is an assumption shared by many philosophers and scientists who study mind in nature. It states that the difference in mind between different creatures is one of degree not kind. It is an attractive thesis, as it can serve as a basis for the application of evolutionary reasoning in studying other minds. The mental continuity thesis, however, is by no means self-evident. If it is to figure as a premise that warrants evolutionary approaches in the study of other minds, it needs to be substantiated. What reasons do we have for accepting that minds exist on a continuum? What are the relevant entities that secures the difference in degree and not kind? An uncritical admission of the mental continuity thesis has historically led to unfounded anthropomorphism (e.g., anecdotal cognitivism). Morgan’s canon, a methodological principle whose intention is to ward against such anthropomorphism, states that explanations of animal behaviors should never invoke complex cognitive processes or mechanisms unless there is compelling independent evidence for doing so. Morgan’s canon thus seems to have an uneasy relationship with the mental continuity thesis. As Morgan’s canon urges us to avoid invoking human-based complex cognitive processes in our explanations of behavior in non-human organisms, how are we to reconcile this with the view that the only difference between the human mind and that of other creatures is one of degree not kind? In other words, what counts as compelling evidence for invoking “human-like” cognitive process that highlight a difference in degree and not kind in our explanations of non-human behavior? We suggest that the concept of homology may be a way to justify the use of seemingly anthropomorphic language and explanation in conceptualizing non-human minds and behavior. However, the scope of this justification is limited. Homology can only play a role of justifying the mental continuity thesis within a restricted taxonomic scope. Specifically, we argue that there is a “goldilocks” zone in which homologies can be optimally used in the role of justifying claims concerning mental continuity across species.
